A pipe joint with earthquake-proof function has, at the same time, an expansion/contraction function and a disengagement prevention function.
For such a pipe joint, a pipe joint of a socket-spigot structure in which a spigot formed at an end of one pipe is inserted inside a socket formed at an end of the other pipe joined with respect to each other is known. The pipe joint is configured so that a lock ring is accommodated in an accommodating groove formed at the inner circumference of the socket and is engaged with a spigot projection formed at the outer periphery of the spigot from the inner part of the socket to exhibit an earthquake-proof function. The lock ring is configured so as to elastically press against the outer periphery of the spigot. A tapered surface is formed on the outer periphery of the lock ring, and due to the reactive force based on the contact of the tapered surface with the inner circumferential edge of the accommodating groove, the lock ring presses against the outer periphery of the spigot and a satisfactory earthquake-proof function is exhibited.
In the pipe joint with earthquake-proof function of such a configuration, since the lock ring is engaged with the spigot projection, an annular groove for fitting the lock ring does not need to be formed on the outer periphery of the spigot to engage the lock ring and the spigot, and thus can be applied to a pipe essentially having a thin thickness. The lock ring is pressed against the outer periphery of the spigot by the action of the tapered surface thereof, and thus a plurality of set bolts do not need to be separately used along the pipe circumference from the outer periphery side of the socket to press the lock ring against the outer periphery of the spigot. Therefore, a sealing structure for the set bolt does not need to be used. Further, after arranging the lock ring within the accommodating groove of the socket and expanding the diameter, the attachment of the lock ring is completed by simply inserting the spigot into the socket, and thus, the application is greatly enhanced compared to when using the set bolt. Moreover, since the set bolt and the sealing mechanism thereof are unnecessary, application failure thereof does not arise, and the reliability of the application enhances.